DIGITAL LIGHT PROCESSING (DLP) technology is a light manipulation technology that is used in a variety of projection systems. A DLP projection system is an image projection system that includes a light source focused on a controllable multiple mirror element, with a lens assembly that focuses the light reflected by the multiple mirror element and projects the reflected light onto an image screen. Each mirror corresponds to an image pixel, and the mirrors are controlled digitally to turn each image pixel on or off. The multiple mirror element may be referred to as a digital mirror device (DMD). A DMD is a semiconductor-based “light switch” array that includes a large number (thousands or millions) of individually addressable, tiltable, mirrors. Each mirror of the DMD is attached to one or more hinges on which the mirror can tilt. Addressing circuitry associated with each mirror generates electrostatic forces that can selectively tilt the mirror. The DMD is a spatial light modulator and provides many advantages to light-steering applications.
For display applications, the DMD is addressed with image data. Responsive to the image data, light is selectively reflected from each mirror for projection. When individual mirrors direct light through an imaging lens, an imaging surface, such as a screen, is selectively illuminated. When the mirror reflects light away from the imaging lens, the reflected light is collected in a discard area. Modulation techniques are used to provide grayscale images. A quick succession of frames is perceived by the viewer as a full motion display.
There are a variety of techniques for generating color displays using a DMD. One approach is to generate multiple images with multiple spatial light modulators (SLMs). For example, one SLM may be used for each of red, green and blue. Each image has a desired intensity and the images are combined to result in a correctly colored display. A second approach is to use a single SLM and generate images for each color (red, green, and blue) sequentially. A white light source may be filtered through a revolving color wheel, and each color reflected by the SLM to produce a desired color in the projected image. The differently colored images are generated so quickly that the eye of the view integrates the images into a correctly colored frame.
DLP technology made possible by the advent of DMD chips has led to the emergence of significant new projection display technology. In addition to commercial success in high definition television, theater projection systems, business and personal projection systems, DLP technology is being applied in the areas of adaptive lighting, medical imaging, photo-finishing, biotechnology applications, lithography, spectroscopy, and scientific instrumentation, and other applications.